1. Field of the Invention
The present invention relates to an electronic throttle control device of an internal-combustion engine configured to control a quantity of intake air to the engine by means of a specific actuator instead of driver's direct control by means of the accelerator pedal, and more particularly, to an electronic throttle control device of an internal-combustion engine suitably used as an electronic throttle control device of an engine or an outboard engine of an water eject propulsion ship that sails on water using thrust produced by ejecting water backwards.
2. Background Art
There has been an engine output control device having an electronic throttle valve provided in an intake channel of the engine and driven by an electric actuator to open/close the intake channel. This engine output control device adjusts a quantity of intake air to the engine by controlling the opening/closing of the electronic throttle value, and thereby controls an output torque of the engine. An example of the engine output control device of this kind in the related art is disclosed, for example, in JP-A-1-177431. The cited document discloses a technique to automatically switch the engine torque characteristics in response to a manipulation quantity of the accelerator pedal to suit the driver's tendency for driving manipulations. This allows the driver to drive the vehicle always with the most comfortable driving feeling.
A quantity of intake air to control the engine output is determined on the basis of a throttle opening degree. The throttle opening degree is determined on the basis of an accelerator opening degree. Hence, when the accelerator opening is increased to the fullest extent, so is the throttle opening degree, and the engine output reaches the maximum output.
However, in a case where the maintenance of the hydraulic system or the cooling system of the engine is poor, when the engine output control is performed in response to the accelerator opening degree adjusted by the driver, the engine may be damaged by overheating. Also, when an inexperienced driver starts a small jet propulsion ship by carelessly manipulating the accelerator pedal to the fullest extent, the ship may be accelerated abruptly, which possibly makes the driving condition unstable.